With the development of modern communications technologies, a communications system has an increasingly high requirement on communication efficiency. To achieve faster and more accurate data transmission, the communications system mostly uses an MIMO (multiple-input multiple-output) technology and a phase array technology. A phase shifter with high-precision phase control plays a key role in the MIMO and phase array technologies. Most existing phase shifters use a microstrip coupling manner. A microstrip is a common signal transmission line. In addition, a coplanar waveguideis also a signal transmission line.
The phase shifter includes at least two structures: a reference structure and a phase shift structure. The reference structure implements a phase shift Φ° at a frequency, and the phase shift structure implements a phase shift (Φ+ψ)° at the frequency. A phase difference ψ° between the two structures is a required differential phase shift. When the phase difference ψ° between the reference structure and the phase shift structure within a passband is a fixed value, a constant differential phase shift can be implemented within the passband.
However, a phase shifter in the prior art has a relatively large size or volume and high cost. This is not helpful for design of a multi-phase feed network including a phase shifter.